1. Field of the Invention
This invention relates generally to a deflection yoke for use with a color cathode ray tube to deflect electron beams generated therein, and more particularly to such a deflection yoke which is aimed to be use with an in-line multibeam cathode ray tube for omitting or simplifying a dynamic convergence correcting means.
2. Description of the Prior Art
Recently, a color cathode ray tube in which a plurality of electron beams are laid in a plane, namely, an in-line cathode ray tube has been actively employed. With the in-line cathode ray tube, a deflection yoke having a horizontal deflection winding which produces a horizontal magnetic field of the pincushion type and a vertical deflection winding which produces a vertical magnetic field of the barrel type is usually used for mitigating misconvergence of the electron beams. For such a deflection yoke, the combination of a saddle shaped horizontal deflection winding and a toroidal vertical deflection winding is popular.
The use of the above mentioned deflection yoke with the in-line cathode ray tube, however, still causes the misconvergence, especially at peripheral portions of a screen of the cathode ray tube. For example, when the beams laid in a line which are properly converged at a central portion of the screen are horizontally deflected, the space between the beam spots on the screen gradually increases in proportion as the deflection angle of the beam increases and, as a result at both side portions on the screen the misconvergence which is too much to be ignored arises. To avoid this misconvergence, generally, a dynamic convergence correcting device has been provided in addition to the deflection yoke. Such a correcting device is, however, so troublesome to adjust or control and besides results in increased cost. Further, some deflection yokes have been proposed for deflecting the beams laid in a line with proper convergence at the whole area of the screen without the use of the dynamic convergence correcting device. Such deflection yokes have the horizontal and vertical windings both of which are wound toroidally with specially arranged winding distribution and therefore the yokes are hard to be manufactured.